1. Field of the Invention
The invention relates generally to the field of power supply circuits, and more specifically to voltage regulating circuits in which a plurality of voltage regulator modules supply power to a common load. In the invention, regulation in the modules is achieved by a common control signal, and each of the modules has an under- and over-voltage detector which determines whether the voltage supplied by it is within a predetermined range or outside thereof, and if the voltage is outside, switches the module out of the circuit.
2. Description of the Prior Art
In many applications, it is advantageous to have multiple power supply modules supply regulated voltage to a common load. For example, the redundant supplies permit power to the load to be uninterrupted in the event of the failure of one of the modules. Furthermore, in some cases, current demands may exceed the capability of a single module at the rated voltage. Accordingly, additional power supply modules are provided to supply the excess current to allow the rated voltage to be maintained.
A number of arrangements have been used to remove an individual power supply module in the event of failure. Failure can result in an over-voltage, which can damage a load circuit and can also result in under-voltage, which can draw current from the proplerly functioning module which may be required by the load circuit. In some prior arrangements, when one of the power supplies fail, both of the power supply modules are disconnected from the load, effectively turning off the load. In other arrangements, the individual power supply modules each include a circuit that is cross-connected to sense failure in the other module, and disconnects the other from the load in the event of failure therein. In still other arrangements a common circuit senses the voltage provided by both of the modules, and switches a module out of the circuit if the voltage is outside of a preselected range.